This invention relates generally to joints for connecting one section of tubular piping to an adjacent piping section, and is particularly concerned with expansion joints having bellows for compensating for thermal expansion effects.
In known pressure balanced expansion joints, the end of one pipe is joined to the end of an adjacent pipe via a bellows arrangement having a central balance bellows and a pair of opposite end bellows for connection to the respective pipe ends. The central bellows has tie rings at each end and each end ring is pinned to rings secured to the outer ends of the respective end bellows. The bellows allows for thermal expansion and contraction in the piping system in the axial direction. However, since the tied rings must always remain parallel, any lateral offsets result in corresponding lateral offsets in the bellows. Such lateral displacements are very detrimental to bellows and often result in shearing of the bellows. This produces a low cycle life and restricted total offset capability. It also results in high forces being transmitted to the piping system. Any angulation of any end or tie ring will result in angulation of all bellows in the system.